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Basic facts


The 2009 influenza A (H1N1) pandemic site is no longer being updated. However, updated pandemic 2009 evaluations are available on the influenza pandemic preparedness site, together with the summaries of the pandemic.

The 2009 influenza A(H1N1) pandemic was declared over in August 2010 by the World Health Organization. Europe has now entered a new inter-pandemic phase of seasonal influenza. For updated information, see the seasonal influenza site. For information regarding pandemic preparedness, including post-pandemic plans, see the influenza pandemic preparedness site.






Q&A on the 2009 pandemic
Frequently asked questions on pandemic (H1N1) 2009, updated 08 October 2009.

Information for travellers
The 2009 pandemic influenza is being reported from an increasing number of locations all over the world. Therefore, precautionary measures for travellers become increasingly important. Updated 18 May 2009.

Origin of the 2009 pandemic influenza A(H1N1) virus
Influenza A: Single stranded RNA virus with eight different genetic segments, when two viruses co-infect the same cell, new viruses can be produced that contain segments from both parental strains (a re-assortment)...

2009 pandemic timeline
This ECDC time-line of the 2009 pandemic runs from the first described cases in California in April 2009 to July 10th 2010 when the WHO Director General declared that the pandemic was over.

Seasonal influenza versus the 2009 pandemic
Table comparing seasonal influenza 2000/1 to 2008/9 and 2009 pandemic influenza, listing the ten characteristics whereby the new pandemic virus differs from the ‘old’ seasonal especially as it appeared in its later years.

Mortality from influenza
Comparing deaths from seasonal and pandemic influenza.

Animals and H1N1
First report of transmission of the pandemic A(H1N1) 2009 influenza virus from humans to birds.





Definition of a Pandemic
The emergence of influenza A virus significant different genetically from circulating human influenza A viruses (i.e. many or most of the population are non-immune to the new virus) with the following three characteristics: able to infect humans, able to cause disease in humans, able to spread from human to human quite easily

WHO pandemic phases
Pandemic phase one:  No animal influenza virus circulating among animals has been reported to cause infection in humans. Pandemic phase two: An animal influenza virus circulating in domesticated or wild animals is known to have caused infection in humans and is therefore considered a specific potential pandemic threat.

Pandemics of the 20th Century
1918 - 1919 Spanish Influenza, 1957 - 1958 Asian Flu, 1968 - 1969 Hong Kong Flu.

Q&A on pandemic preparedness
What is influenza? What is a pandemic? What happens during a pandemic – how many people are affected?









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